1. Field of the Invention
This invention generally relates to powered, food ingredient grinding machines, such as powered coffee bean grinders, and more particularly to control systems and control methods for such grinding machines.
2. Discussion of the Prior Art
Known powered food ingredient grinders, or grinder assemblies are well known. They generally have a frame, an ingredient hopper and a grinding chamber with an inlet for receiving unground ingredient from the hopper, powered grinding blades for grinding the ingredient and an outlet mounted to the frame. An electric motor is mechanically linked to the powered grinding blades, and when electrical power is applied to the electric motor the blades are caused to rotate and grind any ingredient that may be contained within the grinding chamber. The coffee beans or other ingredient to be ground is dumped into the hopper. A gate closure at the bottom of the hopper is opened during grinding to drop ingredient into the grinding chamber. A mounting member removably mounts a brew basket with a paper filter beneath the grinding chamber. The ground ingredient passes from the grinding chamber through an open outlet at the bottom of the chamber and drops into the brew basket.
It is known in the control systems for known grinders to start a grinding cycle by manually actuating a start button after one of a plurality of preselected grinding amounts are selected and then to automatically stop the grinding after a preselected time period after the start of the grinding cycle having a duration corresponding to the preselected amount that has been selected. When the grinding cycle is started the closure gate of the hopper outlet is opened automatically and simultaneously electrical power is applied to the motor to start rotation of the grinding blades. When the time period associated with the selected amount has lapsed, the closure gate is closed and generally simultaneously the electrical power is removed from the motor and the grinding blades stop grinding.
One of the problems or disadvantages in the known food ingredient grinders that the present inventor has determined is that because the amount of ingredient that is ground is determined strictly based on the length of time that the hopper outlet closure gate is held open, depending upon the moisture content and density of the ingredient and the relative size of the ingredient particles, greater or lesser amounts of coffee may be passed from the hopper to the grinder during identical time periods associated with the different preselected time periods that the closure gate is kept open for a given grinding cycle. This can result in brew strength inconsistency between successive brews using ingredients from different grinding cycles that are supposed to have the same quantity of ingredient for each cycle but which are in fact different amounts.
Another problem with known food ingredient grinders is that due to the grinding blades being stopped approximately simultaneously with the closure of the hopper outlet, residual amounts of ground ingredient will remain in the grinding chamber and in the manifold or chute from the grinding chamber to the ground ingredient outlet. This residual ground ingredient can then contaminate subsequent ingredient of a different type that is to ground in the same grinding chamber. This again can lead to inconsistent taste of a beverage brewed from the contaminated ground ingredient.
It is therefore the object of the present invention to provide a food ingredient grinder and method of grinding in which the aforementioned problems are reduced or eliminated.
This is achieved in part by providing in a grinder assembly for grinding a food ingredient having a frame, an ingredient hopper and a grinding chamber with an inlet for receiving unground ingredient from the hopper, powered grinding blades for grinding the ingredient and an outlet mounted to the frame, a control system, comprising means for mounting a brew basket in alignment with the grinding chamber outlet to receive ground ingredient, means for directly measuring the quantity of ground ingredient received within the brew basket and means responsive to the measuring means for controlling the powered cutting blades.
In the preferred embodiment the directly measuring means includes means for measuring the net weight of the ingredient within the brew basket including means for weighing the brew basket and the ingredient contained within the brew basket to determine the gross weight of both the ingredient and the brew basket, means for automatically subtracting the weight of only the brew basket from the gross weight to determine the net weight of only the ingredient in the brew basket. Preferably, the controlling means includes means for storing a preselected ingredient quantity and means responsive to the measuring means for terminating power to the powered cutting blades after the quantity of ground ingredient received within the brew basket equals the preselected quantity.
Thus, in accordance with the food ingredient grinding method of the present invention, in a grinder assembly for grinding a food ingredient having a frame, an ingredient hopper and a grinding chamber with an inlet for receiving unground ingredient from the hopper, powered grinding blades for grinding the ingredient and an outlet mounted to the frame, the ingredient is ground by performing the steps of mounting a brew basket in alignment with the grinding chamber outlet to receive ground ingredient, directly measuring the quantity of ground ingredient received within the brew basket, and responding to the measuring means for controlling the powered cutting blades.
In accordance with another important aspect of the invention, provided in a grinder assembly for grinding a food ingredient having a frame, an ingredient hopper with an outlet, and a grinding chamber with an inlet for receiving unground ingredient from the hopper, an electric motor, powered grinding blades in the grinding chamber for grinding the ingredient, and an outlet chute mounted to the frame for passing ground ingredient out from the grinding chamber is a control system, comprising a closure member mounted for movement between a nonblocking position to a blocking position in which passage of unground ingredient from the ingredient hopper to the grinding chamber is blocked, an actuator for automatically moving the closure member from the nonblocking position to the blocking position when a preslected amount of ingredient has been ground during a grinding cycle, and means for automatically terminating power to the electric motor only after a preselected time period after automatic movement by the actuator of the closure member from the nonblocking position to the blocking position.
Preferably, the automatically terminating means includes means for sensing when the actuator has moved the closure to the blocking position, and a timer for measuring the preselected time period, means responsive to lapse of the preselected time period being measured by the timer to terminate power to the electric motor.
Thus, in accordance with the method of controlling a grinder assembly for grinding a food ingredient having a frame, an ingredient hopper with an outlet, and a grinding chamber with an inlet for receiving unground ingredient from the hopper, an electric motor, powered grinding blades in the grinding chamber for grinding the ingredient, and an outlet chute mounted to the frame for passing ground ingredient out from the grinding chamber, the grinder assembly is controlled by perforamance of the steps of automatically moving a closure member from a nonblocking position to a blocking position blocking position in which passage of unground ingredient from the ingredient hopper to the grinding chamber is blocked when a preslected amount of ingredient has been ground during a grinding cycle and automatically terminating power to the electric motor only after a preselected time period after automatic movement by the actuator of the closure member from the nonblocking position to the blocking position. Preferably, in accordance with the method of controlling the step of automatically terminating includes the steps of sensing when the actuator has moved the closure to the blocking position, measuring the preselected time period, and responding to lapse of the preselected time period being measured by the timer to terminate power to the electric motor. Preferably, the time period is on the order of seven seconds.